Cable Including Non-flammable Micro-particles - Patent 7244893 by Patents-111

VIEWS: 2 PAGES: 11

More Info
									


United States Patent: 7244893


































 
( 1 of 1 )



	United States Patent 
	7,244,893



 Clark
 

 
July 17, 2007




Cable including non-flammable micro-particles



Abstract

A data communication cable including a plurality of twisted pairs of
     insulated conductors, each twisted pair including two electrical
     conductors, each surrounded by an insulating layer and twisted together
     to form the twisted pair, and a jacket substantially enclosing the
     plurality of twisted pairs of insulating conductors, wherein the
     insulating layer includes a dielectric material including a plurality of
     micro-particles. In one example, the jacket material may also include a
     plurality of micro-particles. The micro-particles, in one example, are
     made of a non-burnable and/or non-smokeable material such as, for
     example, glass or ceramic.


 
Inventors: 
 Clark; William T. (Lancaster, MA) 
 Assignee:


Belden Technologies, Inc.
 (St. Louis, 
MO)





Appl. No.:
                    
10/862,767
  
Filed:
                      
  June 7, 2004

 Related U.S. Patent Documents   
 

Application NumberFiling DatePatent NumberIssue Date
 60477519Jun., 2003
 

 



  
Current U.S. Class:
  174/113R
  
Current International Class: 
  H01B 11/02&nbsp(20060101)
  
Field of Search: 
  
  






 174/102SC,110R,113R,113C,110A,112,110F
  

References Cited  [Referenced By]
U.S. Patent Documents
 
 
 
483285
September 1892
Guilleaume

867659
October 1907
Hoopes et al.

1008370
November 1911
Robillot

1132452
March 1915
Davis

1700606
January 1929
Beaver

1883269
October 1932
Yonkers

1940917
December 1933
Okazaki

1976847
October 1934
Gordon et al.

1977209
October 1934
Sargent

1995201
March 1935
Delon

2218830
October 1940
Rose et al.

2501457
March 1950
Thelin

2538019
January 1951
Lee

2882676
April 1959
Bryan et al.

3055967
September 1962
Bondon

3176065
March 1965
Alexander et al.

3328510
June 1967
White

3340112
September 1967
Davis et al.

3559390
February 1971
Staschewski

3603715
September 1971
Edhardt et al.

3622683
November 1971
Roberts et al.

3644659
February 1972
Campbell

3649744
March 1972
Coleman

3819443
June 1974
Simons et al.

3881052
April 1975
Britz et al.

3911200
October 1975
Simons et al.

4034148
July 1977
Lang

4255303
March 1981
Keogh

4283459
August 1981
Urban et al.

4319940
March 1982
Lang

4487992
December 1984
Tomita

4500748
February 1985
Klein

4595793
June 1986
Arroyo et al.

4605818
August 1986
Arroyo et al.

4629285
December 1986
Carter et al.

4644098
February 1987
Norris

4647714
March 1987
Goto

4654476
March 1987
Barnicol-Ottler et al.

4697051
September 1987
Beggs et al.

4710594
December 1987
Walling et al.

4767891
August 1988
Biegon et al.

4777325
October 1988
Siwinski

4778246
October 1988
Carroll

4784462
November 1988
Priaroggia

4788088
November 1988
Kohl

4800236
January 1989
Lemke

4828352
May 1989
Kraft

4847443
July 1989
Basconi

4866212
September 1989
Ingram

4892683
January 1990
Naseem

4912283
March 1990
O'Connor

4970352
November 1990
Satoh

4987394
January 1991
Harman et al.

5010210
April 1991
Sidi et al.

5015800
May 1991
Vaupotic et al.

5037999
August 1991
Van Deusen

5043530
August 1991
Davies

5068497
November 1991
Krieger

5073682
December 1991
Walling et al.

5077449
December 1991
Cornibert et al.

5097099
March 1992
Miller

5107076
April 1992
Bullock et al.

5132488
July 1992
Tessier et al.

5132490
July 1992
Aldissi

5132491
July 1992
Mulrooney

5142100
August 1992
Vaupotic

5146048
September 1992
Yutori et al.

5149915
September 1992
Brunker et al.

5155304
October 1992
Gossett et al.

5170010
December 1992
Aldissi

5173961
December 1992
Chiasson

5177809
January 1993
Zeidler

5180890
January 1993
Pendergrass

5192834
March 1993
Yamanishi et al.

5206485
April 1993
Srubas et al.

5212350
May 1993
Gebs

5216202
June 1993
Yoshida et al.

5220130
June 1993
Walters

5222177
June 1993
Chu et al.

5245134
September 1993
Vana, Jr. et al.

5253317
October 1993
Allen et al.

5254188
October 1993
Blew

5298680
March 1994
Kenny

5304739
April 1994
Klug et al.

5313020
May 1994
Sackett

5371484
December 1994
Nixon

5393933
February 1995
Goertz

5397863
March 1995
Afzali-Ardakani et al.

5399813
March 1995
McNeill et al.

5418878
May 1995
Sass et al.

5424491
June 1995
Walling et al.

5493071
February 1996
Newmoyer

5514837
May 1996
Kenny et al.

5541361
July 1996
Friesen et al.

5544270
August 1996
Clark et al.

5574250
November 1996
Hardie et al.

5576515
November 1996
Bleich et al.

5658406
August 1997
Walling et al.

5666452
September 1997
Deitz, Sr. et al.

5699467
December 1997
Kojima et al.

5767441
June 1998
Brorein et al.

5789711
August 1998
Gaeris et al.

5821466
October 1998
Clark et al.

5821467
October 1998
O'Brien et al.

5834697
November 1998
Baker et al.

5883334
March 1999
Newmoyer et al.

5888100
March 1999
Bofill et al.

5900588
May 1999
Springer et al.

5920672
July 1999
White

5936205
August 1999
Newmoyer

5952607
September 1999
Friesen et al.

5952615
September 1999
Prudhon

5956445
September 1999
Deitz, Sr. et al.

5969295
October 1999
Boucino et al.

5990419
November 1999
Bogese, II

6037546
March 2000
Mottine et al.

6074503
June 2000
Clark et al.

6091025
July 2000
Cotter et al.

6150612
November 2000
Grandy et al.

6153826
November 2000
Kenny et al.

6162992
December 2000
Clark et al.

6194663
February 2001
Friesen et al.

6248954
June 2001
Clark et al.

6255593
July 2001
Reede

6272828
August 2001
Walling et al.

6273977
August 2001
Harden et al.

6288340
September 2001
Arnould

6300573
October 2001
Horie et al.

6303867
October 2001
Clark et al.

6319604
November 2001
Xu

6355876
March 2002
Morimoto

6441308
August 2002
Gagnon

6462268
October 2002
Hazy et al.

6531222
March 2003
Tanaka et al.

6566607
May 2003
Walling

6570095
May 2003
Clark et al.

6596944
July 2003
Clark et al.

2003/0132021
July 2003
Gareis

2004/0050584
March 2004
Hager et al.

2004/0247916
December 2004
MacDonald et al.



 Foreign Patent Documents
 
 
 
6-52727
Feb., 1994
JP

6-103824
Apr., 1994
JP



   Primary Examiner: Nguyen; Chau N.


  Attorney, Agent or Firm: Lowrie, Lando & Anastasi, LLP



Parent Case Text



RELATED APPLICATIONS


This application claims priority under 35 U.S.C. .sctn. 119(e) to U.S.
     Provisional Application Ser. No. 60/477,519, entitled "DATA CABLE
     INCLUDING MICRO-PARTICLES," filed on Jun. 11, 2003, which is herein
     incorporated by reference in its entirety.

Claims  

What is claimed is:

 1.  A data communication cable comprising: a plurality of twisted pairs of insulated conductors, each twisted pair comprising two electrical conductors, each surrounded by an
insulating layer and twisted together to form the twisted pair;  and a jacket substantially enclosing the plurality of twisted pairs of insulated conductors;  wherein the insulating layer comprises a dielectric material comprising a first plurality of
micro-particles embedded in the dielectric material;  and wherein the micro-particles consist of solid glass particles.


 2.  The data communication cable as claimed in claim 1, wherein the jacket comprises a dielectric material comprising a second plurality of micro-particles.


 3.  The data communication cable as claimed in claim 2, wherein the second plurality of micro-particles are substantially spherical in shape.


 4.  The data communication cable as claimed in claim 1, further comprising a separator disposed among the plurality of twisted pairs of insulated conductors.


 5.  The data communication cable as claimed in claim 4, wherein the separator comprises a material having a second plurality of micro-particles disposed therein.


 6.  The data communication cable as claimed in claim 1, wherein the number of the first plurality of micro-particles within the insulating layer is controlled so as to provide a desired effective dielectric constant of the insulating layer.


 7.  The data communication cable as claimed in claim 1, further comprising a light pipe disposed proximate a surface of the jacket.


 8.  The data communication cable as claimed in claim 7, wherein the light pipe comprises a material that is conformable to the surface of the jacket.


 9.  The data communication cable as claimed in claim 7, wherein the light pipe has a predetermined color that serves to identify a characteristic of the data communication cable.


 10.  The data communication cable as claimed in claim 1, wherein the insulating layer comprises a thermoplastic material.


 11.  The data communication cable as claimed in claim 1, wherein the insulating layer is constructed with an appropriate combination of micro-particles and dielectric material such that the insulation layer is suitable for use as a single-layer
insulation.


 12.  The data communication cable as claimed in claim 1, wherein the micro-particles are substantially spherical in shape and have a diameter of between approximately 50 micrometers and 300 micrometers.


 13.  A data communication cable comprising: a plurality of twisted pairs of insulated conductors, each twisted pair comprising two electrical conductors, each surrounded by an insulating layer and twisted together to form the twisted pair;  a
jacket substantially enclosing the plurality of twisted pairs of insulated conductors;  and a separator disposed among the plurality of twisted pairs of insulated conductors so as to separate at least one twisted pair of insulated conductors from others
of the plurality of twisted pairs of insulated conductors;  wherein the jacket includes a dielectric material comprising a first plurality of micro-particles, the first plurality of micro-particles being substantially spherical in shape and having a
diameter of between approximately 50 micrometers and 300 micrometers;  and wherein the separator includes a dielectric material having solid glass micro-particles embedded therein.


 14.  The data communication cable as claimed in claim 13, wherein the micro-particles comprise a non-burnable material.


 15.  The data communication cable as claimed in claim 13, wherein the micro-particles comprise a non-smokeable material.


 16.  The data communication cable as claimed in claim 13, wherein the first plurality of micro-particles are glass.


 17.  The data communication cable as claimed in claim 13, wherein the first plurality of micro-particles are filled with a substance having at least one property that changes as a function of thermal conditions of the cable.


 18.  The data communication cable as claimed in claim 13, wherein the insulating layer comprises a second plurality of micro-particles arranged within the insulating layer.


 19.  The data communication cable as claimed in claim 13, wherein first plurality of micro-particles include at least one of diamond dust, a ceramic material, solid glass particles, and a porous material.


 20.  The data communication cable as claimed in claim 13, wherein the first plurality of micro-particles comprise fluoropolymer micro-particles.


 21.  The data communication cable as claimed in claim 13, wherein the solid glass micro-particles are substantially spherical in shape and have a diameter in a range of about 50 micrometers to about 300 micrometers. 
Description  

BACKGROUND OF INVENTION


1.  Field of Invention


The present invention is directed to cables employing non-burnable and/or non-smokeable materials, particularly to plenum-rated twisted pair cables using such materials for insulation and jacketing.


2.  Discussion of Related Art


Buildings such as office buildings, apartments and other facilities designed for temperature regulation, often include an air space or plenum between the ceiling and floor of successive floors of the building.  The plenum is often contiguous
throughout the floor and permits warm or cool air to be circulated throughout the building to regulate temperature.  Because plenums offer accessibility to the various parts of a building and due to the general convenience of air conduits that typically
extend throughout a facility, cabling structures, for instance, the structured cabling of an office local area network (LAN), are often wired through the plenum.


Should a fire occur in, for example, an office building, the walls, insulation and other fire retardant material are often capable of containing the fire within some portion of the building.  However, fires that reach the plenum tend to draft and
spread to other parts of the building quickly, particularly when the plenum is employed for other purposes and contains flammable material.  Unless the communication cables employed in the plenum are flame and/or smoke retardant, a fire that has breached
the plenum may ignite the cabling structures which may spread smoke and fire throughout a building.  This may quickly intensify and increase the severity of a fire, making it more likely that burn and/or asphyxiation injuries to the occupants of the
building will result and increasing the damage that may be done to the building.


Accordingly, various fire codes and in particular the National Electric Code (NEC) prohibits the use of cables in the plenum unless they have been first tested and exhibit satisfactory smoke and fire retardation.  The various requirements set
forth by the NEC, often referred to generally as the plenum rating, may be satisfied in a series of burn tests provided by, for example, the Underwriters Laboratory (UL).


Plenum rated cables are often made from various fluoropolymer materials.  For example, insulating layers formed around the individual wires of a cable are often made from a fluoroethylenepropylene (FEP) material and jackets formed about the cable
may be made up of an ethylene tetra fluoroethylene copolymer (ETFE) compound.  Other fluoropolymers such as polytetrafluoroethylene (PTFE) may be employed in plenum rated cables as well.  Such fluoropolymers are known to generally exhibit smoke and fire
retardation characteristics sufficient to pass the burn tests, for example, the "peak smoke" and "average smoke" requirements.


However, fluoropolymer materials are relatively expensive and increase the production costs of manufacturing plenum rated cables.  In addition, although fluoropolymers may be generally flame and smoke retardant, under intense flame and/or heat
conditions, fluoropolymers may burn and produce smoke.


SUMMARY OF INVENTION


According to one embodiment, a data communication cable comprises a plurality of twisted pairs of insulated conductors, each twisted pair comprising two electrical conductors, each surrounded by an insulating layer and twisted together to form
the twisted pair, and a jacket substantially enclosing the plurality of twisted pairs of insulating conductors, wherein the insulating layer includes a dielectric material comprising a plurality of micro-particles.  In one example, the micro-particles
may be glass or ceramic or another non-burnable and/or non-smokeable material.


In another example, the jacket may comprise a dielectric material including a second plurality of micro-particles, that may be mixed with the jacket material or embedded therein.  The second plurality of micro-particles may be, for example, made
of a non-burnable and/or non-smokeable material such as, but not limited to, glass or ceramic.  In yet another example, the second plurality of micro-particles may be filled with a substance having at least one property that changes as function of
thermal conditions of the cable.  According to yet another example, the second plurality of micro-particles may filled with a substance having at least one property that changes as function of a frequency of electromagnetic signals propagating through
the cable.


According to another embodiment, the cable may further comprise a separator disposed among the plurality of twisted pairs of insulated conductors.  The separator may also comprise a material having a third plurality of micro-particles, which may
be embedded therein or may be mixed with the separator material.


According to another embodiment, an insulated conductor comprises a conductor, an insulating layer surrounding the conductor so as to form the insulated conductor, the insulating layer comprising a dielectric material including a plurality of
micro-particles, which may be embedded in the insulating layer or mixed with the material forming the insulating layer, wherein the plurality of micro-particles are made of at least one of a non-burnable material and a non-smokeable material.  One or
more twisted pairs may be made using such insulated conductors.  These twisted pairs may, in turn, be used in a data communication cable. 

BRIEF DESCRIPTION OF DRAWINGS


The accompanying drawings, are not intended to be drawn to scale.  In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral.  For purposes of clarity, not every
component may be labeled in every drawing.  In the drawings:


FIG. 1A is a first cross-sectional view of one embodiment of a cable according to aspects of the invention;


FIG. 1B is a second cross-sectional view of the embodiment of a cable described in FIG. 1A.


FIG. 2 is a cross-sectional view of another embodiment of a cable according to aspects of the invention; and


FIG. 3 is a cross-sectional view of another embodiment of a cable according to aspects of the invention.


DETAILED DESCRIPTION


Various embodiments and aspects thereof will now be discussed in detail with reference to the accompanying figures.  It is to be appreciated that this invention is not limited in its application to the details of construction and the arrangement
of components set forth in the following description or illustrated in the drawings.  The invention is capable of other embodiments and of being practiced or of being carried out in various ways.  Examples of specific implementations are provided herein
for illustrative purposes only.  In particular, acts, elements and features discussed in connection with one embodiment are not intended to be excluded from a similar role in other embodiments.  For example, the various compositions, arrangements and
configurations of micro-particles described in any embodiment should be considered as contemplated for each of the embodiments described herein.  Also, the phraseology and terminology used herein is for the purpose of description and should not be
regarded as limiting.  The use of "including," "comprising," or "having," "containing", "involving", and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.


In order to achieve plenum rated cables, manufacturers often employ materials that generally exhibit desirable burn and smoke characteristics such as, for example, any of various fluoropolymer compounds.  However, such materials are often
relatively expensive.  Accordingly, the more of such material that is present in a cable, the higher the cost of manufacturing a plenum rated cable.


Applicants have identified of various methods of reducing or eliminating expensive compounds from data communications cables.  For example, according to some embodiments, fluoropolymer material may be replaced in the cable by various less
expensive materials that also have desirable flame and/or smoke characteristics, such that the cost of the cable may be reduced.  In one example, the fluoropolymers used in conventional plenum cables may be replaced with non-burnable and/or non-smokeable
materials.  Such non-burnable and/or non-smokeable material may improve the burn characteristics of the cable over those manufactured with fluoropolymer material because the non-burnable and/or non-smokeable materials, respectively add no ignitable mass
and do not produce smoke.


It is to be appreciated that for the purposes of this specification, the term "non-burnable" refers generally to materials that do not ignite in the presence of heat and/or flame.  For example, materials (e.g., glass or ceramic) that tend to melt
rather than burn or have essentially infinite flash points are considered as non-burnable material.  The term "non-smokeable" refers generally to material that essentially produces no, or minimal (less than conventional "low-smoke" materials), smoke when
exposed to heat, ignited and/or caused to change states.


In one embodiment, non-burnable and/or non-smokeable materials may be used in connection with fluoropolymer materials such that less fluoropolymer material is required to achieve the same or better burn characteristics as a conventional cable
using only fluoropolymers.  Alternatively, non-burnable and/or non-smokeable materials may be used in place of fluoropolymers to provide a relatively inexpensive plenum rated cable that meets or exceeds the burn characteristics of conventional plenum
cables employing fluoropolymers.


Therefore, at least one embodiment of the present invention includes an electrical conductor, which may be, for example, a metal wire, a group of wires stranded together, a composite of metals, a fiber, or any other conductor used in the industry
and known in the art.  The electrical conductor may be surrounded by an insulating layer that includes a non-burnable and/or non-smokeable material, to form an insulated electrical conductor.  According to one example, a plenum-rated data communications
cable includes a plurality of insulated electrical conductors wherein the insulating material does not include any fluoropolymer material.  In another example, a jacket of the plenum-rated cable may also not include any fluoropolymer materials.  In yet
another example, the jacket may include a non-burnable and/or non-smokeable material.


Applicant has identified and appreciated that micro-particles may be used to improve various characteristics of data communication cables.  Micro-particles are small structures or shapes that may be added to another material to form a composite
material, mixture or slurry.  In one example, micro-particles used in embodiments of cables may have a diameter in a range of about 1 micrometer (.mu.m) to about 300 .mu.m.  However, it is to be appreciated that the micro-particles may have other sizes
and may be larger or smaller depending, for example, on the application for which they may be used.  Micro-particles may be solid, hollow, partially hollow, porous or filled with other agents and/or materials, and may be of any general shape. 
Micro-particles may be shaped such that they form an empty micro-volume, cavity or void.  Such a micro-volume may be open or closed or contain another agent, substance and/or material.  Micro-particles may be mixed with or embedded in various materials
and/or used as fillers in various compounds, colloids and/or mixtures.


For example, developments in materials have led to the production of various micro-particles, such as the micro-spheres manufactured by 3M, Emerson Cuming, Inc., and others.  These glass micro-spheres, which may be made, for example, from sodium
borosilicate, can be manufactured with desired dimensions and may be made hollow, solid, porous or filled.  Micro-particles may be formed to different shapes other than spheres, however, spheres have generally desirable manufacturing properties. 
Micro-particles may be amalgamated into a single material or added to other materials, for example, as a filler in a mixture or slurry.  It should be appreciated that micro-particles are not limited to the materials or vendors noted above and other
micro-particles may be used in any of the embodiments described below.


Applicant has identified and appreciated that micro-particles may be included in various materials (e.g., thermoplastics) that are used to construct insulating layers, separators, binders, jackets and other components or portions of data
communication cables.  Applicants have further recognized that the addition of micro-particles formed from non-burnable and/or non-smokeable materials to cables may result in the cable having a variety of generally desirable properties including
increased fire and smoke retardation, improved electrical characteristics, improved strength and weight characteristics, lower cost, and other advantages.


Referring to FIG. 1B, there is illustrated a cross-sectional view of one embodiment of a cable according to aspects of the invention.  The cable 100 includes four twisted pairs of insulated conductors 50a, 50b, 50c, 50d that may be bundled
together and jacketed with a jacket 60.  Each twisted pair 50 comprises two insulated conductors 52a, 52b.  Each insulated conductor comprises an electrical conductor 10a, 10b surrounded by an insulating layer 12a, 12b.  It is to be appreciated that
although FIG. 1B illustrates a cable including four twisted pairs of conductors, the invention is not so limited and the principles of the invention may be applied to cables having any number of twisted pairs.  In addition, the principles of the
invention are not limited to twisted pair cables and may be applied, for example, to cables using individual insulated conductors (as opposed to twisted pairs), optical cables, and the like.  Also, in twisted pair cables, each twisted pair may be
different from other twisted pairs in the cable (e.g., in terms of twist lay length, material used etc.), or some or all of the twisted pairs may be similar or the same.


Referring to FIG. 1A.  there is illustrated a twisted pair 50a in close-up cross-section.  According to one embodiment, the insulating layers 12a, 12b may be formed of a thermoplastic material having a plurality of micro-particles 5 distributed
throughout the material.  For example, micro-particles 5 may be glass or ceramic, or another non-burnable and/or non-smokeable material (such as, for example, diamond dust) that may be added as filler to the thermoplastic material before the material is
extruded over the conductors to form insulating layers 12a and 12b, or may be applied andlor provided in any other suitable way.  For example, another way of providing a particle-impregnated layer may include providing a bath of ultraviolet-curable resin
having micro-particles mixed with the resin and running an item to be coated (such as a conductor) through the bath prior to curing the resin.


While micro-particles 5 are illustrated in FIGS. 1A and 1B as having a generally spherical shape, it should be appreciated that micro-particles may be formed to any desired shape or be of an arbitrary shape.  For example, micro-particles may be
shards of arbitrary or amorphous shape resulting from breaking, grinding, or other rendering a desired material into particulate matter.  Moreover, micro-particles may be formed having micro-volumes or small cavities that are void, porous or contain air
and/or other substances.  For example, micro-particles 5 may include flame and/or smoke retardant materials such as carbon dioxide.


Micro-particles are not limited to non-burnable or non-smokeable material.  For example, micro-particles may be formed from a flame and smoke retardant material such as any of various fluoropolymer compounds.  Such fluoropolymer micro-particles
may be embedded in, or mixed with, a less expensive material to achieve a reduced cost insulating layer having desirable burn characteristics.


In general, micro-particles may be provided in a number of ways to both improve the insulating layers resistance to flame and smoke and to facilitate forming a cable that can satisfy the various burn tests utilized by the UL in order to achieve a
plenum rating.  For example, non-burnable and/or non-smokeable micro-particles may reduce the amount of smoke producing material in a cable, improving the cables performance in peak and average smoke tests.  Similarly, less expensive micro-particles
having superior burn and smoke characteristics may reduce the amount of or eliminate altogether costly fluoropolymers conventionally used to provide a plenum rated cable.  For example, the micro-particles may be used in connection with relatively
inexpensive thermoplastic such as polyolefin to achieve satisfactory burn characteristics without having to resort to expensive fluoropolymer materials.


Certain electrical properties of a twisted pair may depend on the materials used in construction.  For example, the characteristic impedance of a twisted pair is related to several parameters including the diameter of the conductors 10a, 10b, the
center-to-center distance between the conductors, the dielectric constant of insulating layers 12a, 12b, etc. The center-to-center distance is proportional to the thickness of the insulating layers and the dielectric constant depends in part on the
properties of the material.  The micro-particles used in constructing the insulating layers may be chosen such that insulating layers achieve a desired effective dielectric constant.  For instance, hollow or air-filled micro-particles may be embedded in
a dielectric material forming the insulating layer, thereby lowering the effective dielectric constant of the insulating layer.  The number of such micro-particles embedded in the insulating layer may be controlled so as to control the effective
dielectric constant of the resulting composite (dielectric plus micro-particles) insulating layer material.


Accordingly, the dielectric constant may be reduced and/or tailored to meet the requirements of a particular design.  Reduced dielectric constants for insulated conductors may yield higher transmission propagation speeds and have generally
desirable skew characteristics.  In general, it is to be appreciated that micro-particles may be used to tailor any characteristic of the cable, such as, but not limited to, characteristic impedance, burn characteristics, skew, crosstalk, etc.


It should be appreciated that various aspects of the present invention may be applied to other components of a data communication cable including, but not limited to, separators, binders, jackets, and the like.  For example, many high performance
cables employ some form of separator between the individual twisted pairs in a cable to further reduce crosstalk.  Examples of such separators include, but are not limited to, cross-web separators and various configurable core separators that facilitate
simple provision of any number of desirable arrangements available for separating twisted pairs or certain desired pairs in a multi-pair cable.


Referring to FIG. 2, there is illustrated another embodiment of a twisted pair cable 200 including a separator 202 that is disposed between the twisted pairs 204.  In the illustrated example, each of the twisted pairs is separated from adjacent
pairs by a flange of a cross or "+" shaped separator 202.  However, it is to be appreciated that the separator 202 may have any of a variety of shapes and is not limited to a "+" shaped structure.  In conventional plenum cables, separators are often made
from relatively expensive fluoropolymer materials.  In one embodiment, separator 202 may be made of any of various materials used in manufacturing separators, for example, a thermoplastic material.  As shown, a plurality of micro-particles 206 are
included in the material forming separator 202.  As discussed above in connection with FIG. 1, the micro-particles may be of any shape and may comprise various flame and smoke resistant materials including glass, ceramic, fluoropolymers, etc. The
micro-particles may comprise open or closed volumes and may contain other agents, for example, like flame retardant substances such as carbon dioxide.


According to one embodiment, illustrated in FIG. 2, the insulating layers 56 of the twisted pairs 204 may contain micro-particles 206.  However, it should be appreciated that one, a plurality, or all of the twisted pairs 204 may be formed without
micro-particles being in the insulating layers 56.  Moreover, any of the various arrangements and compositions of micro-particles and materials described in connection with the insulators of FIG. 1 may be applied to any of various separators (e.g.,
separator 202) either individually or in combination with the insulators.


Thus, according to aspects of various embodiments, cables may be formed according to the invention using micro-particles 206 in all or any of the insulating layers 56 of the twisted pairs 204 and also optionally in the separator 202, in any
combination.  For example, the embodiment illustrated in FIG. 2 includes micro-particles in all of the insulating layers 56 and the separator 202.  However, in another embodiment, for example, only one or two of the twisted pairs may have insulating
layers including micro-particles and a separator may or may not include micro-particles.


Referring to FIG. 3, there is illustrated another embodiment of a cable 300 according to aspects of the invention.  The cable 300 includes a plurality of twisted pairs 302 that may be separated by a separator 202 and are held in place and
proximate each other and the separator 202 by a jacket 304.  Conventional plenum-rated cables often include jackets made from a flame and smoke retardant PVC material.  According to one embodiment of the present invention, as illustrated in FIG. 3, the
jacket 304 may be made to include a plurality of micro-particles 306 as part of, or embedded in or mixed with, the material forming the jacket 304.  As discussed above, although the micro-particles 306 are illustrated as being generally spherical, they
may be of any shape or structure including solid, hollow, porous, filled with another substance to reduce flame and/or smoke and may otherwise be arranged, composed and provided according to any of the various alternatives and methods described in the
foregoing.


In addition, it is to be appreciated that in any embodiment, the micro-particles used in the jacket, the separator and the insulating layers may be the same or different shape, size and structure.  For example, in one embodiment, all the
micro-particles used in each of the jacket, separator and insulating layers may be solid glass or ceramic spheres or shards.  In another embodiment, any or all of the insulating layers of the twisted pairs may include air-filled micro-particles while the
separator may include solid glass micro-particles.  It is to be appreciated that there are many possible variations of the type, number, shape etc., of micro-particles used in any of the insulating layers, the jacket and the separator.  All of these
possible variations are intended to be part of this invention and covered by this disclosure.


Referring again to FIG. 3, according to another aspect of the invention, the micro-particles 306 may be filled with a chemical or substance adapted to indicate at least one characteristic of the environment of the cable.  For example, some of
micro-particles 306 may include a chemical having a property (e.g., color) that changes as a function of ambient thermal conditions.  Many PVC jackets are vulnerable to cracking when handled at low temperatures.  Accordingly, a color change of the
micro-particles may alert a cable installer that the temperature is too low to safely pull the cable and that the integrity of the cable may be at risk should it be twisted, bent, cornered or otherwise handled roughly.


According to another embodiment, some of micro-particles 306 may include substances that have a property (e.g., color) that changes as a function of the frequency of proximate electromagnetic radiation.  Accordingly, the micro-particles may
respond to the frequency of the data transmission of the cable as indication of the performance of the particular cable, or in response to radiation in the environment.  In yet another embodiment, some of the micro-particles 306 may be filled with one
type of chemical, for example that is able to indicate environmental conditions of the cable while others of the micro-particles 306 may be filled with substances that are adapted to indicate characteristics (such as frequency of data transmission) of
the cable itself.  Accordingly, so-called "smart-cables" can be adapted to be responsive both to internal and external operating characteristics of the environment.


Applicant has further appreciated that various testing, diagnostic and informational benefits may be derived by employing one or more light pipes within a cable.  A light pipe refers generally to any light transmissive medium that facilitates the
propagation of optical energy.  For example, light pipes may be constructed from lucite, acrylic, optical fiber, etc.


According to one aspect of the invention, one or more light pipes 308 are embedded into the jacket of a cable.  Preferably, the light pipe 308 would run or span the length of the cable such that light signals may be propagated, for example, from
the source end of a cable to its termination.  A light pipe may be produced as a cylindrical structure or may be provided as a generally planar material conformable to a surface of a cable such as, for example, the cable jacket.  A light pipe may be
employed in a cable as a device used to aid in identifying the cable.  For example, in a structured cable system, the light pipe 308 could be illuminated at its port in a network computer room or at its connection in a telecommunications closet so that
it can be quickly and easily determined which cables are ultimately connected at which ports.


In addition, network failures or faulty connections may be easily identified and rectified by illuminating the problem node via its cable connection.  Various other diagnostic and identification tasks may be achieved by the provision of a light
pipe, such as tracing and general troubleshooting.  Furthermore, the light pipe may be adapted to transmit information, for example, as a serial communications such that more sophisticated information may be relayed via the light pipe.


Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art.  Such alterations, modifications, and
improvements are intended to be part of this disclosure, and are intended to be within the scope of the invention.  Accordingly, the foregoing description and drawings are by way of example only.


* * * * *























								
To top